Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - voltage regulators - DC DC switch controllers QSOP 20

General Description

The MAX1960/MAX1961/MAX1962 high-current, high-

efficiency voltage-mode step-down DC-DC controllers

operate from a 2.35V to 5.5V input and generate output

voltages down to 0.8V at up to 20A. An on-chip charge

pump generates a regulated 5V for MOSFET drive.

Additionally, adaptive dead-time drivers allow a

wide variety of MOSFETs to be used without risking

shoot-through.

Fixed-frequency PWM operation and external synchro-

nization make these controllers suitable for telecom

and datacom applications. The operating frequency is

programmable to either 500kHz or 1MHz, or from

450kHz to 1.2MHz with an external clock. A clock output

is provided to synchronize another converter for 180°

out-of-phase operation. A high closed-loop bandwidth

provides excellent transient response for applications

with dynamic loads.

Lossless current sensing in the MAX1960 and

MAX1961 is achieved by monitoring the drain-to-source

voltage of the low-side external FET. The current limit is

scalable to accommodate a wide variety of MOSFETs

and load currents. The MAX1962 has 10% accurate

sense-resistor-based current limiting.

The MAX1960 and MAX1962 have an adjustable output

voltage from 0.8V to 4.95V. The MAX1961 and

MAX1962 have four preset output voltages (1.5V, 1.8V,

2.5V, and 3.3V) and feature 0.5% voltage accuracy

over temperature, line, and load variations. The

MAX1960 and MAX1961 also feature voltage-margining

control inputs that shift the output voltage up or down

by 4% for system testing.

Applications

ASIC, FPGA, DSP, and CPU Core and I/O Voltages

Cellular Base Stations

Telecom and Network Equipment

Server and Storage Systems

Features

 0.5% Accurate Output

 Operates from 2.35V to 5.5V Supply

 Generates Low Output Voltage Down to 0.8V

 On-Chip Charge Pump Provides 5V Gate Drive

 Ceramic or Electrolytic Capacitors

 94% Efficiency

 External Synchronization from 450kHz to 1.2MHz

 500kHz/1MHz Fixed-Frequency PWM Operation

 Fast Transient Response

 Two Converters Can Operate 180° Out-of-Phase

 ±4% Voltage Margining for System Test

 10% Accurate Current Sensing (MAX1962)

 Adaptive Dead Time Prevents Shoot-Through

MAX1960/MAX1961/MAX1962

2.35V to 5.5V, 0.5% Accurate, 1MHz PWM

Step-Down Controllers with Voltage Margining

________________________________________________________________

Maxim Integrated Products

Ordering Information

19-2740; Rev 1; 6/09

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,

or visit Maxim’s website at www.maxim-ic.com.

EVALUATION KIT

AVAILABLE

PART TEMP RANGE PIN-PACKAGE

MAX1960EEP -40°C to +85°C 20 QSOP

MAX1961EEP -40°C to +85°C 20 QSOP

MAX1962EEP -40°C to +85°C 20 QSOP

Pin Configurations and Selector Guide appear at the end

of the data sheet.

MAX1960

CTL1

COMP

REF

GND

FSET/SYNC

CLKOUT

BST

PGND

C+ C-

INPUT

2.35V TO 5.5V

CLKOUT

180° OUT-OF-PHASE

OUTPUT

0.8 TO 0.87

✕ V

UP TO 20A

CTL2

ILIM

OPTIONAL

SYNCHRONIZATION

VOLTAGE

MARGINING

AND ON/OFF

Typical Operating Circuit

Summary of content (29 pages)

PAGE 1
9-2740; Rev 1; 6/09 KIT ATION EVALU E L B A AVAIL 2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining The MAX1960/MAX1961/MAX1962 high-current, highefficiency voltage-mode step-down DC-DC controllers operate from a 2.35V to 5.5V input and generate output voltages down to 0.8V at up to 20A. An on-chip charge pump generates a regulated 5V for MOSFET drive. Additionally, adaptive dead-time drivers allow a wide variety of MOSFETs to be used without risking shoot-through.
PAGE 2
MAX1960/MAX1961/MAX1962 2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining ABSOLUTE MAXIMUM RATINGS VCC, CTL_, CS, FSET/SYNC, SEL, EN, OUT to GND ..........................................................-0.3V to +6V ILIM, COMP, REF, FB, CLKOUT, C- to GND ..............................................-0.3V to VAVDD + 0.3V C+ to GND.............-0.3V to higher of VVCC + 1V or VVDD + 0.3V VDD, AVDD to GND ..............-0.3V to higher of VVCC - 0.3V or 6V DL to PGND .........
PAGE 3
2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining (VVCC = 3.3V, Circuits of Figures 9–12, TA = 0°C to +85°C. Typical values are at TA = +25°C, unless otherwise noted.) PARAMETER VDD Output Voltage Reference Voltage (No Load) Reference Load Regulation MAX UNITS 2.7V ≤ VVCC ≤ 5.5V, ILOAD = 1mA to 50mA CONDITIONS 4.75 MIN 5.25 V 2.35V ≤ VVCC ≤ 2.7V, ILOAD = 1mA to 35mA, C1 = 4.7µF, C6 = 22µF (Note 1) 4.45 5.25 V 2.35V ≤ VVCC ≤ 3.
PAGE 4
MAX1960/MAX1961/MAX1962 2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining ELECTRICAL CHARACTERISTICS (VVCC = 3.3V, Circuits of Figures 9–12, TA = -40°C to +85°C, unless otherwise noted.) (Note 2) PARAMETER CONDITIONS VCC Input Voltage Range MAX UNITS 2.35 MIN TYP 5.50 V VCC Input Voltage UVLO Rising or falling 1.95 2.3 V VDD Input Voltage UVLO Rising or falling 3.90 4.45 V Output Voltage 0.
PAGE 5
2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining (VVCC = 3.3V, Circuits of Figures 9–12, TA = -40°C to +85°C, unless otherwise noted.) (Note 2) PARAMETER CONDITIONS MIN TYP MAX UNITS Current-Limit Threshold (Negative Direction, Adjustable, VLX - VPGND) MAX1960/MAX1961, RILIM = 160kΩ 90 125 RILIM = 400kΩ 245 296 DH Gate-Driver On-Resistance VBST - VLX = 5V, pulling up or down 3.5 Ω DL Gate-Driver On-Resistance (Pullup) DL high state 3.
PAGE 6
Typical Operating Characteristics (Circuit of Figure 9, TA = +25°C, unless otherwise noted.) 80 VOUT = 1.8V 70 80 VOUT = 2.5V VOUT = 1.8V 70 VOUT = 1.5V 100 90 VOUT = 1.8V VOUT = 1.5V 70 60 60 50 50 100 10 0.1 1 0.1 100 10 1 100 10 LOAD CURRENT (A) LOAD CURRENT (A) LOAD CURRENT (A) EFFICIENCY vs. LOAD CURRENT WITH 15A 500kHz CIRCUIT, 5V INPUT OUTPUT VOLTAGE vs. INPUT VOLTAGE, 1MHz OUTPUT VOLTAGE vs. INPUT VOLTAGE, 500kHz VOUT = 1.8V VOUT = 1.5V 2.5 2.5V OUTPUT DROPOUT 2.0 1.
PAGE 7
2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining 600 500 400 300 FSET/SYNC = GND 200 5.0 4.9 VIN = 3.3V 4.8 4.7 VIN = 2.5V 4.6 C1 = 1µF C6 = 4.7µF 5.1 MAX1960 toc11 5.1 5.2 CHARGE-PUMP OUTPUT VOLTAGE (V) 700 C1 = 0.47µF C6 = 2.2µF MAX1960 toc10 FSET/SYNC = VCC 800 5.0 4.9 4.8 4.7 VIN = 2.5V 4.6 VIN = 3.3V 100 4.5 4.5 -15 10 35 60 0 85 50 100 0 200 150 C10, C11, C12 = 0.47µF C6 = 2.2µF 5.1 5.0 4.9 VIN = 2.5V 4.8 4.7 4.
PAGE 8
MAX1960/MAX1961/MAX1962 2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining Typical Operating Characteristics (continued) (Circuit of Figure 9, TA = +25°C, unless otherwise noted.) VOLTAGE-MARGINING STEP RESPONSE 7.5A TO 15A TO 7.
PAGE 9
2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining PIN NAME FUNCTION Clock Output. Connect to FSET/SYNC of a second converter to operate 180° out-ofphase. CLKOUT swings from VCC to GND. CLKOUT is low in shutdown (see the Operating Frequency and Synchronization section). MAX1960 MAX1961 MAX1962 1 1 1 CLKOUT 2 2 2 FSET/SYNC 3 3 — ILIM — — 3 EN Enable. Drive high for normal operation. Drive low or connect to GND for shutdown mode.
PAGE 10
MAX1960/MAX1961/MAX1962 2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining Pin Description (continued) PIN NAME FUNCTION MAX1960 MAX1961 MAX1962 15 15 15 C- Charge-Pump Flying Capacitor Negative Connection. Use a 0.47µF ceramic capacitor at 1MHz, and 1µF between 450kHz and 950kHz. 16 16 16 C+ Charge-Pump Flying Capacitor Positive Connection. Use a 0.47µF ceramic capacitor at 1MHz and 1µF between 450kHz and 950kHz.
PAGE 11
2.35V to 5.5V, 0.
PAGE 12
MAX1960/MAX1961/MAX1962 2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining Operating Frequency and Synchronization The MAX1960/MAX1961/MAX1962 operating frequency is set externally to either 500kHz or 1MHz. For 500kHz operation, connect FSET/SYNC to GND, or for 1MHz operation, connect FSET/SYNC to VDD. Alternately, an external clock from 450kHz to 1.2MHz can be applied to SYNC. A clock output (CLKOUT) that is 180° out-of-phase with the internal clock is also provided.
PAGE 13
2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining MAX1960/MAX1961/MAX1962 Inductor operating point. This choice provides tradeoffs between size, transient response, and efficiency. Choosing higher inductance values results in lower inductor ripple current, lower peak current, lower switching losses, and, therefore, higher efficiency at the cost of slower transient response and larger size.
PAGE 14
DH 0.22µH, 2.8mW, ILIMIT = 18A RL IPEAK L LX ILOAD INDUCTOR CURRENT MAX1960/MAX1961/MAX1962 2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining MAX1962 DL R R = 33Ω C C = 4.7µF IVALLEY CS TIME OUT Figure 3. Inductor Current Waveform Figure 4. Using the Inductor Resistance as a Current-Sense Resistor with the MAX1962 ates a 128 clock cycle counter.
PAGE 15
2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining VDIP RESR ≤ ILOADSTEP(MAX) In applications with less severe load steps, maximum ESR may be governed by what is needed to maintain acceptable output voltage ripple: VRIPPLE(P−P) RESR ≤ LIR × ILOAD(MAX) To satisfy both load step and ripple requirements, select the lowest value from the above two equations. The capacitor is usually selected by physical size, ESR, and voltage rating, rather than by capacitance value.
PAGE 16
MAX1960/MAX1961/MAX1962 2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining VIN GAIN (dB) DH LO VOUT LX DL C0 MAX1960 R3 FB R2 C3 R4 R1 COMP fz1 fp1 C2 fz2 fp2 fp3 FREQUENCY C1 Figure 5. Type 3 Compensation Network Figure 6. Transfer Function for Type 3 Compensation where: VIN(MAX) = Maximum input voltage VRAMP = Oscillator ramp voltage = 0.85 x 106/fS, where fS = switching frequency LO = Output inductance If C2 < 10pF, it can be omitted.
PAGE 17
2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining GMOD(DC) = VIN VRAMP where VRAMP = 0.85 × 106 / fS. The pole frequency due to the inductor and output capacitor is: fPMOD = fPEA = fZEA = f fZESR < fC ≤ S 5 The loop-gain equation at the crossover frequency is: VFB × GEA(fC ) × GMOD(fC ) = 1 VOUT where: GEA(fC ) = gmEA × RC 1 The output capacitor is usually comprised of several same value capacitors connected in parallel.
PAGE 18
MAX1960/MAX1961/MAX1962 2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining 5 CC = 2π × RC × fPMOD A small capacitor CF, can also be added from COMP to GND to provide high-frequency decoupling. CF will add another high-frequency pole (fPHF) to the error-amplifier response. This pole should be greater than 100 times the error-amplifier zero frequency to have negligible impact on the phase margin.
PAGE 19
2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining ERROR AMPLIFIER MODULATOR OUTPUT FILTER V1 0.8V R1 VIN/VRAMP Gm RS R2 R3 L1 C9 V2 RESR RLOAD COUT Figure 7. Open-Loop Transfer Model (4) Gate threshold voltage (VTH(MIN)) (5) Turn-on/turn-off times (6) Turn-on/turn-off delays At high switching rates, dynamic characteristics (parameters 1, 2, 5, and 6) that predict switching losses may have more impact on efficiency than RDS(ON), which predicts DC losses.
PAGE 20
MAX1960/MAX1961/MAX1962 2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining where VIN(MAX) is the maximum value of the input voltage, tFALL and tRISE are the fall and rise time of the MOSFET, I L(PEAK) and I L(VALLEY) are the maximum peak and valley inductor current, and fS is the PWM switching frequency: IL(PEAK) = IOUT(MAX) × (1 + 0.5 × LIR) and IL(VALLEY) = IOUT(MAX) × (1 - 0.5 × LIR) where LIR is the peak-to-peak inductor ripple current divided by the load current.
PAGE 21
2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining MAX1960/MAX1961/MAX1962 Table 3. Component List for Application Circuits PART APP. CIRCUIT C1 1, 2, 3 C2 1, 2, 3, 4 15A OUTPUT 1MHz 15A OUTPUT 500kHz 0.
PAGE 22
MAX1960/MAX1961/MAX1962 2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining Table 4. R1, R3, and C9 Component Values for 1MHz Operation VIN VOUT = 3.3V VOUT = 2.5V VOUT = 1.8V VOUT = 1.5V R1 (kΩ) R3 (kΩ) C9 (µF) R1 (kΩ) R3 (kΩ) C9 (µF) R1 (kΩ) R3 (kΩ) C9 (µF) R1 (Ω) R3 (kΩ) 5V 3.12 1.2 0.0068 2.13 9.1 0.01 1.24 6.8 0.01 876 5.5 C9 (µF) 0.01 3.3V — — — — — — 1.24 2.7 0.01 876 2.4 0.01 2.5V — — — — — — 1.24 3.9 0.01 876 3.
PAGE 23
2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining MAX1960/MAX1961/MAX1962 C1 INPUT 2.7V TO 5.5V C+ C4 C- VCC AVDD C2 R5 CTL1 VDD CTL2 BST D1 COMP MAX1960 C6 R7 DH N1 C5 C9 REF C13 OUTPUT DOWN TO 0.8V L1 LX C3 R8 DL C8 R3 N2 C14 GND FSET/SYNC CLKOUT PGND ILIM R4 CLKOUT N.C. R1 FB R2 Figure 9.
PAGE 24
MAX1960/MAX1961/MAX1962 2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining C1 INPUT 2.7V TO 5.5V C+ C4 C- VCC AVDD C2 R5 CTL1 VDD D1 BST CTL2 COMP C6 MAX1961 R7 DH N1 C5 C9 REF C13 L1 OUTPUT 2.5V LX C3 R8 DL C8 R3 N2 C14 GND FSET/SYNC CLKOUT PGND ILIM R4 CLKOUT VSEL OUT Figure 10.
PAGE 25
2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining MAX1960/MAX1961/MAX1962 C1 INPUT 2.7V TO 5.5V C+ C4 C- VCC AVDD C2 R5 VDD D1 COMP C6 BST EN MAX1962 R7 DH N1 C5 C9 REF C13 L1 R6 OUTPUT DOWN TO 0.8V LX C3 R8 DL C8 R3 N2 C14 GND FSET/SYNC CLKOUT CLKOUT PGND CS OUT R1 VSEL FB R2 Figure 11.
PAGE 26
MAX1960/MAX1961/MAX1962 2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining D3 D2 D4 C11 C10 INPUT 2.35V TO 3.6V C+ C12 C4 C- VCC D5 AVDD C2 R5 VDD D1 BST EN COMP C6 MAX1962 R7 DH N1 C5 C9 REF C13 LX L1 R6 OUTPUT 1.5V C3 R8 DL C8 R3 N2 C14 GND FSET/SYNC CLKOUT CLKOUT VSEL PGND CS OUT FB VDD Figure 12.
PAGE 27
2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining MAX1960/MAX1961/MAX1962 C1 0.47µF INPUT 2.7V TO 5.5V C+ C2 5 x 10µF C4 1µF C- VCC AVDD R5 10Ω CTL1 VDD CTL2 BST C6 2.2µF D1 COMP C10 33pF C9 820pF R3 10kΩ MAX1960 REF C8 0.22µF C5 0.1µF N1 C13 4700pF L1 OUTPUT 2.5V, 15A LX DL N2 C3 4 x 47µF TAIYO-YUDEN JMK325BJ476MN R8 1Ω C14 4700pF GND FSET/SYNC CLKOUT DH R7 1Ω PGND ILIM R4 390kΩ CLKOUT N.C. R9 680Ω C7 560pF R1 6.84kΩ FB R2 3.
PAGE 28
MAX1960/MAX1961/MAX1962 2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining Pin Configurations TOP VIEW TOP VIEW CLKOUT 1 20 LX CLKOUT 1 20 LX FSET/SYNC 2 19 DH FSET/SYNC 2 19 DH N.C.
PAGE 29
2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining REVISION NUMBER REVISION DATE 0 1/03 Initial release 1 6/09 Updated Electrical Characteristics and Compensation with Ceramic Output Capacitors sections. DESCRIPTION PAGES CHANGED — 4, 16 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied.